This application is based on and incorporates herein by reference Japanese Patent Applications No. 2001-74901 filed on Mar. 15, 2001, and No. 2001-332748 filed on Oct. 30, 2001.
1. Field of the Invention
The present invention relates to a power transmission system that transmits torque generated by a driving unit such as an engine and an electric motor to a driven unit such as a pump and a compressor. The present invention is suitably applied to a power transmission system transmitting a power from an engine to a compressor used for an air conditioning apparatus for a vehicle.
2. Description of Related Art
A power transmission system used for an air conditioning apparatus for a vehicle transmits torque to a compressor from an engine, i.e., a reciprocation-type internal combustion engine. Therefore, the system incurs a larger fluctuation in torque than a system for transmitting power generated by an electrically rotating power source such as an electric motor. However, if a torque-fluctuation reducing member for reducing the torque fluctuation is simply used for the power transmission system, the size of the power transmission system is increased.
In view of the foregoing problems, it is an object of the present invention to provide a power transmission system having a compact size, which can sufficiently reduce torque fluctuation.
According to the present invention, in a power transmission system for transmitting torque from a driving unit to a driven unit, a first rotating member rotated by the driving unit has a first torque transmitting surface, a second rotating member connected to the driven unit is disposed coaxially with the first rotating member to have a second torque transmitting surface, and an elastically-deformable torque transmitting member is disposed to contact the first and the second torque transmitting surfaces to transmit torque from the first rotating member to the second rotating member. The first and the second torque transmitting surfaces are arranged opposite to each other in a radial direction of the first and the second rotating members, the first torque transmitting surface has a plurality of first concaves (concavities) each of which is recessed toward a side opposite to the second torque transmitting surface, the second torque transmitting surface has a plurality of second concaves (concavities) each of which is recessed toward a side opposite to the first torque transmitting surface, and the torque transmitting member is disposed between the first and the second concaves opposite to each other. Accordingly, when torque is applied to the first rotating member, the first rotating member and the second rotating member are relatively displaced, and the torque transmitting member is shearing-deformed while being press-deformed. Therefore, the torque is transmitted from the first rotating member to the second rotating member by the reaction force in response to a vector component of the deformation of the torque transmitting member, parallel to the rotation direction, and a torque fluctuation can be sufficiently reduced by the compression-deformation and the shearing deformation of the torque transmitting member. As a result, the elasticity modulus of the torque transmitting member can be made smaller, and the size of the power transmitting system can be reduced while the torque fluctuation is reduced.
Preferably, the torque transmitting member is a double-layer structure having an outer layer and an inner layer inside the outer layer, the outer layer is made of a material having a predetermined abrasion resistance and a rigidity higher than the inner layer, and the inner layer is made of a material having a predetermined damping characteristic and a predetermined extensibility. Therefore, durability of the power transmitting member can be improved. Further, the torque transmitting member is provided to have a cross-sectional shape where strain, generated when torque acts on the torque transmitting member, is approximately uniformly distributed along an entire cross-section. Therefore, it can prevent cracks from being generated while the durability of the torque transmitting member can be further improved.
The torque transmitting member is provided to have a cross-sectional shape where a connection portion connecting one side end portions of contact surfaces of the torque transmitting member, contacting the first and second torque transmitting surfaces, becomes approximately straight line, and the one side end portions are provided to form a curved surface. More preferably, a radial outer side of the connection portion is tilted toward a rotation backward side relative to a radial direction of the first and second rotating members, when torque is not applied to the torque transmitting member. Accordingly, it can prevent a contact area between the torque transmitting member and the first and second torque transmitting surfaces from being greatly reduced, and it can prevent a contact surface pressure therebetween from being greatly increased.